I just bought a '97 F-150 4x4 std. cab long bed with the 4.6, automatic, and 3.55 limited slip two weeks ago. It has roughly 75,000 miles on it. I'm thrilled with the truck except for one little detail. I've noticed that when I accelerate from a dead stop, something in the rear of the truck is clunking. It feels kind of like something sliding back into the tailgate. It's a firm but not sharp feeling. There is no noise at all. I've gone so far as checking the spare mounting and paying attention to the fuel level as I though maybe it was sloshing back, but neither are the cause. I'm thinking that it may be the rearend. I know that the dealer replaced the wheel seals before I bought it, but other than that I'm in the dark as to it's history. Otherwise, the truck drives great. The dealer gave me a 6 mo./6000 mi. powertrain warranty, but I'd like to have a general idea what is or could be going on before I head for the service department only to be told that there's nothing wrong. Anybody else have this problem? My dad has had a '98 and a '00, both 2WD, and I've never noticed it driving either of them. Thanks in advance for any ideas!

 

Do a gentle power brake and see if it still does it. I would think that would show that it's u joints.

 

I had a 97 with the same problem. The dealer greased the slipyoke where the drive shaft went into the tailshaft on the rear of the transfercase. That solved the problem for me. Hope this helps you...

 

Thanks for the ideas, guys. I'll crawl under it and check out the joints and grease the slip yoke in the morning. Incidentally, it had crossed my mind that it feels like the axle is wrapping up and if the slip yoke is sticky, that may very well cause that. Good call!

 

Mine does something similar, but I think mine is in the transmission... When I first start the truck up, put it in gear, and give it a shot of gas, its almost like something is slipping, then it catches, and makes the truck shudder... Not sure what it is, and havent had it in for servicing.. I'll just wait till something lets go

 

That shudder sounds like one of the plates in your tranny has broke.

 

I have the SAME deal with mine. I've taken it to three different technicians, with all three giving me the same answers..."THAT'S A FORD FOR YA". Fortunataly, I've not had and "problems" with this, but it does make me wonder. Sorry I can't help with the matter, I'll keep watching to see if anyone has a decent answer for the problem.

 

i have a 99 offroad, look in the archives and u will find similar questions. i asked for and they told me its pressure being built up and its not mechanical. doesnt to it all the time just half, like when u gun it.

 

I have the same problem with my 99 F150 4x4. But the dealer thought mine had to do with the lift blocks in between the axle and springs. I have a 4" Rancho suspension lift. I just had mine in the body shop to fix some sheet metal up front, where a girl pulled out in front of me on Christmas Eve, Ho Ho HO..Anyway, they took it to the dealer for an alignment and they said that my motor mounts were broke. I'm wondering if that has anything to do with. They thought that the mounts may have been broken before the accident. I remember the clunk starting just after I high centered the truck playing in some dirt. There was alot of wheel spinning and hopping before we got off that mound. Anyway, I'm getting the mounts replaced soon,so I'll let you know if that imrpoves anything.

Greg

 

Hi BlueOvalRage - we have identical trucks! I have the same problem & was told by other F150 owners it could be driveshaft spin. I had u- joints replaced in June of 2001 & it still does it but that could just be me. Thought I'd share this w/you - hope it helps a little.

 

I have the same truck...I have the same noise...The dealer said they thought that the rear springs needed a "kit"...$56 for the kit and 2 hours of labor... ergo..$200 + I will let you know if this solves the problem. I don't have a clue what the "kit" is...but before they do the work I will find out. It has to do with the rear axle housing rotating...can't be to good for the u-joints or the diff.

 

As I said in my second post, Michael, it feels to me like the axle housing is "wrapping up" or rotating, so this is right in line with your dealer's diagnosis. I would be extremely interested in hearing the results of having your "kit" put in and if it solves the problem, by all means please post the kit part number. It would be greatly appreciated. And yes, cowlady, our trucks are identical! Right down to the color and the CD changer. Is your interior maroon?

 

I believe your "kit" includes the pads in between the springs. I guess the theory is that will reduce the springs from sliding over one another, reducing axle wrap. They replaced mine and there was little or no improvement. I hope you get better results. Once again, my truck has a suspension lift using lift blocks that may contribute to the problem. But I'm surprised to find other folks having similar problems.

Good Luck,
Greg

 

More information from my rear end clunk experience.

I attached a chain from the bottom of the axle to the frame, where the springs attach. I was hoping to keep the axle from swinging back. I think it helped, but the turnbuckle loops came open/bent after very little driving. These were 1/4" or 5/16" steel, and I didn't try any larger ones yet. Based on that experience, I believe that it was axle wrap, a common problem on lifted vehicles. But may also be a problem in general for these trucks.

Greg

 

Hi BlueOvalRage! No - I have the charcoal gray interior but have seen your color in a friend's truck - his is nearly identiacal to ours but is a shortbed. He said that the red/maroon interior is rare! You may have a gold mine in your truck! Hey - a girl can wish, right, even if it's for someone else!